SO2 and NO2 effects on microbial activity in an acid forest soil.

The rate of glucose decomposition and the pH fell in a forest soil (initial pH 4.06) exposed to 1.0 ppm SO2. No such effect was noted if the soil was exposed to 1.0 ppm nitrogen dioxide (NO2). Nitrite but not bisulfite (5μg N or S/g of soil) inhibited O2 consumption and CO2 evolution in the glucose-amended forest soil, and nitrite and bisulfite acted synergistically in inhibiting these processes. Iron and manganese were solubilized when the soil was exposed to 10 ppm SO2, but NO2 caused no such change.